The invention relates to an optoelectronic monitoring device for a motor vehicle.
For example. a monitoring device of this type is disclosed in U.S. Pat. No. 4,867,561 and is used as a rain sensor and consists of an imaging system for imaging water droplets, which are located on the windscreen, on an optoelectronic sensor array which is formed as a CCD-line. The rain sensor comprises an IR-light-emitting unit, whose light for detecting water droplets on the windscreen is directed towards said windscreen and wherein the emitted light is reflected in the event of water droplets being present on the windscreen. The reflected light is directed to an imaging convex lens, behind which is disposed the CCD-line as a photoelectric sensor array. In this case, the lens is used as an imaging system for the purpose of imaging the optical information which is to be detected by the sensor array.
In one embodiment of this previously known rain sensor, two IR-light sources can be used, wherein one is coordinated with the outer surface of the windscreen and the other is coordinated with the inner surface of the windscreen. As a consequence it is possible to differentiate between rain drops located on the outer side of the windscreen and water droplets (condensation) located on the inner side of the windscreen. For this purpose a predetermined number of adjacent transducer elements of the CCD-line is combined to form transducer element groups for evaluation purposes. In so doing, such a group can be allocated to the light source which is provided for the purpose of detecting rain drops, and a further group can be allocated to the light source which is provided for the purpose of detecting condensation.
On the whole this previously known device represents a rain or moisture sensor which can be used exclusively to ascertain whether water droplets are present on the outer side or on the inner side of a windscreen.
In the automotive industry, optical sensors are also used for the purpose of detecting further optical information. For example sensor systems of this type are used for detecting solar altitude, for controlling the headlamps or for monitoring the internal compartment of a vehicle. All of these systems have corresponding photoelectric sensor arrays and corresponding imaging systems.
On the basis of this discussed prior art, it is therefore the object of the invention to propose an optoelectronic monitoring device which renders it possible to detect different optical information of different optical sensor systems.
This object is achieved in accordance with the invention by means of an optoelectronic monitoring device for a motor vehicle having optical imaging systems which are allocated to a plurality of different monitoring objects and which on the output side influence the photosensitive surface of a photoelectric sensor array, consisting of a plurality of photoelectric transducer elements which form individual pixels, in a two-dimensional arrangement which transducer elements generate an electric signal, which corresponds to the light intensity, in dependence upon their respective exposure to light, wherein for the purpose of imaging the optical information which is provided by the imaging system, the output of each imaging system is disposed above a transducer element group which is allocated to this imaging system and consists of one or several transducer elements, and having an evaluation unit which is influenced by virtue of the electric output signals of the sensor array for the purpose of controlling actuators in dependence upon the result of an evaluation of the information relating to the object, which imaging systems are combined in the region of their outputs to form a physical unit and are fixed on a circuit carrier which is allocated to the sensor array.
By virtue of the monitoring device in accordance with the invention, which is allocated a plurality of imaging systems supported expediently by a common holding device which combines the imaging systems, this monitoring device can be used for the most varied optical sensor systems by using a single sensor array. Imaging systems include both image-forming systems, i.e. lenses, or optic fiber systems. Since the output of each imaging system is allocated a predetermined transducer element group of the sensor array, it is possible to allocate in a defined manner predetermined group signals to predetermined imaging systems and thus to predetermined optical information which is to be detected. It is possible that between the individual transducer element groups there are provided transducer element gaps or lines which are not allocated to an imaging system. These transducer elements would render it possible to control the exposure corresponding to the ambient light or to determine the continuous ambient light.
The individual imaging systems are combined in the region of the photoelectric sensor array to form a physical unit and are fixed on the circuit carrier of the sensor array. Therefore, the sensor array is held in a fixed position with respect to the outputs of the imaging systems, so that always the same transducer elements are influenced by the imaging systems even in the event of vehicle vibrations.
When a photoelectric sensor array which is used in a motor vehicle is provided with a lens as one of the imaging systems, the said sensor array is suitable for detecting image-forming information. This type of system can therefore be used, for example, as an internal vehicle compartment monitoring system or also for monitoring the area surrounding the vehicle, i.e. for the purpose of receiving signals in a distance sensing system. When using this sensor array for monitoring the internal compartment of a vehicle, it is expedient to dispose such a sensor array in the region of the internal rearview mirror or in the region of a roof console as a roof module, so that it operates in a rearward direction. The remaining optical information is supplied to the sensor array by means of optic fibers as further imaging systems wherein individual fibers can be used for the purpose of transmitting light intensities or fiber bundles can be used for the purpose of transmitting image-forming information.
This type of photoelectric sensor array having a multi-functional lens system formed by the combination of different imaging systems can also be disposed in a different position in a motor vehicle. The optical information supplied to the sensor array can be filtered with regard to the information which is to be actually detected. Since the sensor array can be formed for the purpose of receiving a large frequency bandwidth, this type of sensor array is suitable at the same time for a wide range of optical sensing systems which can use both IR-light, visible light or UV-light.
In one advantageous embodiment a type of sensor array is provided, whose individual transducer elements can be addressed and selected in a free manner. This type of embodiment produces advantages particularly with respect to an alignment of the sensor array-side outputs of the imaging systems with respect to the photosensitive surface of the sensor array when the two elements are assembled and in the interests of guaranteeing consistent quality. Owing to the similar formation of all of the transducer elements of the sensor array, this design allows the spatial position of a transducer element group to be defined using software. It is then possible to use the software to adjust the transducer element groups in relation to the respective imaging systems. Consequently, it is possible to compensate for any assembly inaccuracies in the arrangement of the imaging systems with respect to the sensor array; the individual transducer element groups can also be adapted using software to suit any changes as a result of operation over a period of many years or as a result of other causes which lead to a deviation in the transducer element group which is defined for an imaging system.
Further advantages of the invention and embodiments are included in the remaining subordinate claims and in the description herein under of one exemplified embodiment.